HOW CONCRETE PRODUCERS MIX READY-MIX

THE THREE SYSTEMS USED TO MIX MATERIALS IN THE FINAL STAGE OF READY-MIX PRODUCTION ARE DEFINED. THESE ARE CENTRAL MIXING, TRUCK OR TRANSIT MIXING, AND SHRINK MIXING WHICH IS A COMBINATION OF THE OTHER TWO. THE TYPES OF MIXING EQUIPMENT UNITS WHICH MAY BE USED AS EITHER TRUCK MIXERS OR AGITATORS ARE REVIEWED AS WELL AS THE MIXING SPEEDS. THE IMPORTANCE OF ADEQUATE MIXING IS EMPHASIZED. THE MIXING TIME VARIABLE AFFECTS CONSISTENCY AND WATER DEMAND. OTHER VARIABLES INDICATED ARE: DISTANCE TO THE JOB SITES, SPEED OF DISCHARGE, FAILURE OF EQUIPMENT, TRAFFIC, WEATHER CONDITIONS, ETC. IT IS EMPHASIZED THAT FRESH CONCRETE MUST BE PROTECTED FROM VERY HIGH AND VERY LOW TEMPERATURES IF IT IS TO DEVELOP TO ITS FULL STRENGTH AND DURABILITY. EXCESSIVELY HIGH TEMPERATURES INCREASE WATER REQUIREMENTS, CAUSE A GREATER LOSS OF SLUMP, AND ACCELERATE CEMENT HYDRATION. THE RAPID INCREASE IN THE DIVERSE USAGE OF CONCRETE HAS BROUGHT ABOUT ADDITIONAL AND MORE RIGID REQUIREMENTS AND CANNOT BE MET ECONOMICALLY USING JUST THE STANDARD MATERIALS. WHILE THERE IS STILL NO SUBSTITUTE FOR GOOD CONCRETING PRACTICES, ADMIXTURES CAN IMPART TO CONCRETE CERTAIN CHARACTERISTICS THAT MAKE FOR BETTER CONCRETE. ADMIXTURES HAVE IMPROVED THE WORKABILITY AND WATER- TIGHTNESS OF CONCRETE, INCREASED DURABILITY AND SUPERFICIAL HARDNESS, DEVELOPED HIGHER RESISTANCE TO COMPRESSIVE STRENGTH, ACCELERATED THE RATE OF STRENGTH AT EARLY STAGES, RETARDED AND ACCELERATED INITIAL SETTING, MODIFIED THE RATE AND CAPACITY FOR BLEEDING, DECREASED THE CAPILLARY FLOW OF WATER, INHIBITED CORROSION AND INCREASED RESISTANCE TO SPECIAL CONDITIONS OF EXPOSURE, IMPROVED BONDING, AND IMPARTED MANY OTHER DESIRABLE CHARACTERISTICS - WITH NO DAMAGE TO THE PROPERTIES INHERENT IN GOOD CONCRETE ITSELF.

  • Supplemental Notes:
    • Vol 20, No 12, PP 38, 40, 42, 2 PHOT
  • Authors:
    • Carbonell, C A
  • Publication Date: 1967-12

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  • Accession Number: 00210708
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 6 1994 12:00AM